JPH09271949A - Method for processing trailing end part in electrogas arc welding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a processing method in which a fault is prevented from being caused in a trailing end in an electrogas arc welding, namely, in which gouging in an object to be welded or generation of a shrinkage hole is prevented in the trailing end of welding without causing a blowhole or an interruption of welding, and in which an electrogas arc welding method can be applied to the connecting part of a column through type building frame. SOLUTION: At the point of time in reaching the trailing end of welding, the welding current is divided into two steps or more and lowered to the final current value. In this case, the final current value is 75% or less of the main welding current, with the decrement per step not more than 20% of the preceding current value. In addition, time is set 10 seconds or longer after the final current value is reached until the current is stopped. Further, when ceramics, copper or copper alloy is used as a tab material for the trailing end, the decrement of the welding current can be expanded to not more than 35%.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vertical electrogas arc welding method using a flux-cored wire, and relates to a method for treating a terminal portion of the electrogas arc welding method for preventing the occurrence of defects at the terminal portion.

[0002]

2. Description of the Related Art Electrogas arc welding is widely used in the fields of shipbuilding and bridges. For example, in the field of shipbuilding, as shown in FIG. 14, a pair of members to be welded 1, 2 arranged vertically and facing each other.
Has a V groove formed between them, and above the groove,
That is, the end tabs 3 and 4 are arranged on the upper edge of the material to be welded. When the members 1 and 2 to be welded arranged in this way are continuously electrogas arc welded from the lower part to the upper part, the weld metal 5 is formed in the groove, and the weld metal 6 reaches the end tabs 3 and 4. It is formed and welding is completed.

At the end of this welding, welding defects such as shrinkage holes, hollows, blow holes, etc. occur. However, in the fields of shipbuilding, bridges, etc., it is a welding mode in which the end tabs 3 and 4 can be arranged on both materials 1 and 2 to be welded.
The weld end portions having many defects are located at the end tabs 3 and 4, and after the welding is completed, the weld metal 6 solidified by the end tabs is cut and removed together with the end tabs 3 and 4, so that the materials to be welded 1 and 2 are welded. It is possible to prevent defects from remaining in the welded metal 5 between them. In this way,
Electrogas arc welding is widely used in the field of shipbuilding and bridges.

[0004]

However, when it is considered that the electrogas arc welding method is applied to a column penetration type joint (a joint between a skin plate of a box column and a flange of a beam) in a building steel frame, The welding end portion cannot be released to the end tab, and the welding defect remains in the welding portion.

FIG. 15 is a perspective view showing a state in which the electrogas arc welding method is applied to a column penetration type joint.
The box plate skin plate 7 and the beam flange 8 are arranged so as to have a T-shape in a plan view, and end tabs 9 and 10 are arranged at the lower end and the upper end of the flange to perform electrogas arc welding. A weld metal 11 is formed between the weld metal 11 and the metal 7. Then, as shown in FIG. Z, at the welding end portion, a cut-out defect occurs on the skin plate 7 side at the end tab 10 portion, and a contraction hole occurs at the central portion of the weld metal 12. Since one of the portions where the welding defect occurs is the skin plate 7, it cannot be cut and removed together with the end tab as in the case of FIG. X, and remains in the welded portion. Therefore, sufficient strength as a joint cannot be obtained, and repair or the like needs to be performed after welding.

When the crater treatment that is performed in ordinary gas shield welding is applied to the end portion of the electrogas arc welding, the entire molten pool has a thick slag layer at the end portion in the vertical electrogas arc welding method. Since it is covered, when the main welding current is rapidly reduced to the crater current, the arc becomes unstable, and blowholes may occur, or welding may be interrupted due to improper energization.

The present invention has been made in view of the above problems, and prevents the occurrence of defects at the end portion in the electrogas arc welding method, that is, without causing the occurrence of blowholes and interruption of welding, the welding end Provide a method for treating the end part of the electrogas arc welding method, which can prevent the occurrence of the scooping and shrinkage hole of the welded member in the welded part and enables the application of the electrogas arc welding method to the column penetration type joint part in the building steel frame The purpose is to do.

[0008]

A method of treating a terminal portion in an electrogas arc welding method according to the first invention of the present application is
When the welding reaches the end portion, there is a step of dividing the welding current into two or more steps to reduce the final current value, and the reduction amount per step is within 20% of the previous current value, and the final current value is set. Is less than or equal to 75% of the main welding current, and the time until the current is stopped after reaching the final current is 10 seconds or more.

Further, the method for treating the end portion in the electrogas arc welding method according to the second aspect of the present invention has a step of dividing the welding current into one or more steps and reducing it to the final current value when the welding reaches the end portion. However, the amount of reduction per step is within 35% of the previous current value, the final current value is 75% or less of the main welding current, and the time until the current is stopped after reaching the final current is 10 seconds. The above is characterized by using ceramic, copper, or a copper alloy material as the tab material of the terminal portion.

In the present invention, the welding current is reduced in a plurality of stages until the welding current reaches a final current of 75% or less of the main welding current at the welding end portion. The reduction rate of the welding current per step is 20% of the current value before that.
After the final current is reduced to 75% or less of the main welding current, the current is stopped for 10 seconds or more. If the tab material at the end is made of a material that does not melt, such as ceramic or copper or copper alloy material (water-cooled or non-water-cooled), or that does not combine with the molten metal when melted, weld it. The width of the current reduction is set to 35 of the welding current before that.
It can be expanded to%. As a result, the molten pool is gradually reduced without causing arc instability at the welding end portion, so that it is possible to prevent the occurrence of a hollow and a contraction hole in the member to be welded. Therefore, even if the welding end portion remains, the joint strength does not decrease and repair is unnecessary.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below.
This will be specifically described with reference to the accompanying drawings. FIG. 1 is a graph showing an embodiment method of the present invention. FIG. 2 is a member layout view showing an electrogas arc welding method applied to a column penetration type joint portion in a building steel frame, FIG. 3 is a view showing the welding method, and FIG. 4 is a view showing a state after completion of welding. First, as shown in FIG. 2, the flange 8 is arranged in a T shape in a plan view on the vertical skin plate 7, and the end tabs 9 and 10 are arranged at the lower end and the upper end thereof, respectively. Then, the backing material 20 made of a steel backing, a water-cooled copper plate or the like is arranged on the back side of the groove.

Then, as shown in FIG. 3, a water cooling pad 21 is arranged on the front surface of the groove, and the skin plate 7 and the backing material 2 are provided.
0, the space surrounded by the flange 8 and the pad 21,
The welding wire 25 is supplied from the tip 24 of the welding torch 23, and the arc 30 is generated to start welding. Deposit 2
1 is supplied with cooling water from the cooling water supply port 22
Cool 1 Further, since the backing material 20 is made of a non-melting member such as a steel backing or a water-cooled copper plate, the slag 29 is solidified in layers between the backing material 21 and the backing material 20, and the flange 8 and the skin plate. 7 is a weld metal 2 whose surface is once melted and solidified, and solidified in the groove.
Both are joined by 8.

A molten metal 27 is formed on the weld metal 26.
Then, the molten slag 28 is further formed on the molten slag 28, and the weld metal is stacked in this laminated state. When the welding is completed, the molten metal is finally solidified in the upper end tab 10.

Thus, in the present embodiment, as shown in FIG. 1, the welding current is gradually reduced at the welding end portion by a reduction amount of 20% or less of the previous current value, and 75% of the main welding current.
Until the following, the welding current is reduced in this manner in stages. And the main welding current is 75
After the final current value is reduced to 10% or less, the current is stopped after 10 seconds or more have passed. By thus reducing the welding current in multiple stages, the molten pool can be gradually reduced without the arc becoming unstable. When the reduction width of the welding current exceeds 20%, arc instability occurs. The final current value is set to 75% or less of the main welding current, but if it is more than this, the size of the molten pool does not become small, so that it is not possible to prevent the occurrence of engraving in the member to be welded. Furthermore, when the time until the current is stopped after reaching the final current value is less than 10 seconds, the molten pool does not become sufficiently small, and the end treatment becomes insufficient.

FIG. 5 is a view showing the vicinity of the welding end portion when a steel tab is used as the end tab 10. Although it is common to use a steel tab as the end tab, the molten slag 2 floating above the molten metal is used.
No. 8 rises in the groove as the welding progresses, and even in the final solidified portion, the slag layer remains with the same thickness. In such a case, as described above, in order to avoid the influence of arc instability from the molten slag layer, the reduction width of the welding current is set to 20%.
It is necessary to:

In FIG. 6, when a water-cooled or non-water-cooled copper tab or a ceramic tab is used as the end tab 10, it does not melt at the time of welding or does not combine with the weld metal even if it melts. When reaching the position, the molten slag coating the surface of the molten metal (molten pool) adheres to the tab material. Therefore, the layer of molten slag becomes thin and the arc is stabilized. For this reason,
Since the end of welding is easier to process and arc instability due to a decrease in current is less likely to occur, the reduction range of welding current can be reduced to 3
It can be expanded to 5% or less. In this way, according to the present embodiment, it is possible to prevent welding defects such as shrinkage holes, cutouts and blow holes at the welding end portion, and even if the welding end portion remains, the joint strength will not deteriorate. Absent.

[0017]

EXAMPLES Examples of the present invention will be described below in comparison with comparative examples. The following Tables 1 to 3 show the processing conditions of the terminal end in the electrogas arc welding method of the present example and the comparative example.

"Welding condition" Flux-cored wire: JISZ3319, YFEG-
22C, diameter 1.6 mm, vertical welding: welding current 380 A, welding voltage 42 V, welding speed 3.0 cm / min (however, the welding speed is automatically adjusted to keep the wire protrusion length constant) Tip shape "Plate thickness: 36 mm, 35 ° L type, Gap: 7 mm" Termination processing condition "Voltage: Appropriate voltage for each current value The welding speed during crater processing is the same as during main welding, with a constant wire protrusion length. Automatically adjusted to hold. Therefore, the current value is lower than the main welding current,
The welding speed is slow.

[0019]

[Table 1]

[0020]

[Table 2]

[0021]

[Table 3]

The groove shape is as shown in FIG. That is, a groove is provided between the skin plate 30 and the flange 31, and a steel backing 32 is used as a backing material for the groove.
Was provided. Groove gap 7mm, groove angle 35 °,
The thickness of the flange 31 is 36 mm. Further, the occurrence status of defects is as shown in FIGS. 9 to 11. However, these figures are sectional views taken along the line AA shown in FIG. In FIG. 8, reference numeral 36 is a weld metal, and in FIG. 9, reference numeral 37 is an end tab. FIG. 9 shows the cut-out defect 33 generated in the skin plate 30. FIG. 10 shows contraction holes 34 generated in the weld metal 36, and FIG. 11 shows blow holes 35. 12 is a view showing the shape of the ceramic tab, and FIG. 13 is a view showing the shape of the water-cooled copper tab.

As shown in Tables 1 to 3, in the embodiments of the present invention, the arc is stable, the skin plate does not have the gouging defect, and the contraction hole and the blow hole do not occur. On the other hand, in the case of the comparative example which is out of the range of the present invention, any of arc instability, hollow defect, shrinkage hole and blow hole occurs.

[0024]

As described above, according to the present invention,
At the end of welding, until reaching the final current of 75% or less of the main welding current, 20% or less of the welding current before that or 35% or less when ceramic or copper plate is used as the tab material at the end. Since the welding current is reduced step by step, the molten pool can be gradually reduced without causing arc instability, and welding defects such as gouging and shrinkage holes can be prevented without causing blowholes and welding interruptions. be able to.

[Brief description of drawings]

FIG. 1 is a graph showing an example method of the present invention.

FIG. 2 is a view showing the arrangement state of each member.

FIG. 3 is a diagram showing an electrogas arc welding method.

FIG. 4 is a diagram showing a state after completion of welding.

FIG. 5 is a diagram showing an operation in the case of a steel tab.

FIG. 6 is a diagram showing an operation in the case of a ceramic tab or a copper tab.

FIG. 7 is a view showing a groove shape.

FIG. 8 is a diagram illustrating a defect occurrence situation.

FIG. 9 is a diagram showing a cut-out defect that has occurred in a skin plate.

FIG. 10 is a diagram showing shrinkage hole defects.

FIG. 11 is a diagram showing blowhole defects.

FIG. 12 is a view showing a ceramic tab.

FIG. 13 shows a water cooled copper tab.

FIG. 14 is a view showing a conventional electrogas arc welding method in which an end tab is provided at the end portion.

FIG. 16 is a perspective view showing a state in which a conventional electrogas arc welding method is applied to a column penetration type joint.

[Explanation of symbols]

 7: Skin plate 8: Flange 9, 10: End tab 11: Weld metal 12: End weld metal 20: Backing material

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] July 15, 1996

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Brief description of drawings

[Correction method] Change

[Correction contents]

[Brief description of drawings]

FIG. 1 is a graph showing an example method of the present invention.

FIG. 2 is a view showing the arrangement state of each member.

FIG. 3 is a diagram showing an electrogas arc welding method.

FIG. 4 is a diagram showing a state after completion of welding.

FIG. 5 is a diagram showing an operation in the case of a steel tab.

FIG. 6 is a diagram showing an operation in the case of a ceramic tab or a copper tab.

FIG. 7 is a view showing a groove shape.

FIG. 8 is a diagram illustrating a defect occurrence situation.

FIG. 9 is a diagram showing a cut-out defect that has occurred in a skin plate.

FIG. 10 is a diagram showing shrinkage hole defects.

FIG. 11 is a diagram showing blowhole defects.

FIG. 12 is a view showing a ceramic tab.

FIG. 13 shows a water cooled copper tab.

FIG. 14 is a view showing a conventional electrogas arc welding method in which an end tab is provided at the end portion.

FIG. 15 is a perspective view showing a state in which a conventional electrogas arc welding method is applied to a column penetration type joint.

FIG. 16 is a diagram showing shrinkage hole defects at the welding end portion.

[Explanation of symbols] 7: Skin plate 8: Flange 9, 10: End tab 11: Weld metal 12: Weld metal at the end 20: Backing material ────────────────── ───────────────────────────────────

[Procedure amendment]

[Submission date] July 15, 1996

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0005

[Correction method] Change

[Correction contents]

FIG. 15 is a perspective view showing a state in which the electrogas arc welding method is applied to a column penetration type joint.
When the box pillar skin plate 7 and the beam flange 8 are arranged so as to be T-shaped in a plan view, and the end tabs 9 and 10 are arranged at the lower end and the upper end of the flange and electrogas arc welding is performed, the flange 8 and the skin plate are formed. A weld metal 11 is formed between the weld metal 11 and the metal 7. Then, as shown in FIG. 16 , in the weld end portion, a cut-out defect occurs on the skin plate 7 side in the end tab 10 portion, and a contraction hole occurs in the center portion of the weld metal 12. One of the parts where the welding defect occurs is the skin plate 7,
It cannot be cut and removed together with the end tab as in the case of No. 14 , and remains at the welded portion. Therefore, sufficient strength as a joint cannot be obtained, and repair or the like needs to be performed after welding.

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0019

[Correction method] Change

[Correction contents]

[0019]

[Table 1]

Claims (2)

[Claims] 1. When the welding reaches the end portion, there is a step of dividing the welding current into two or more stages to a final current value, and the reduction amount per step is within 20% of the previous current value. And the final current value is 75% or less of the main welding current,
The time until the current is stopped after reaching the final current is 10
A method for treating a terminal portion in an electrogas arc welding method, which is characterized in that the time is at least 2 seconds. 2. When the welding reaches the end portion, there is a step of dividing the welding current into one or more steps to a final current value, and the reduction amount per step is within 35% of the previous current value. And the final current value is 75% or less of the main welding current,
The time until the current is stopped after reaching the final current is 10
A method of treating a terminal portion in an electrogas arc welding method, characterized in that a ceramic material, copper, or a copper alloy material is used as a tab material for the terminal portion for at least 2 seconds.